usage msg; xls and overwrite param; descrip bugfix
usage msg; xls and overwrite param; descrip bugfix

+ usage message when no parameters
+ new write XLS and Overwrite flags

* bugfix: 'description' is too many characters (11),
	kudos @dgj32784 on GIS Stack, https://gis.stackexchange.com/a/243359/108

maphew/arcplus,maphew/arcplus